A key feature of long term evolution advanced (LTE-A) is a higher data rate. This is supported by allowing a wireless transmit/receive unit (WTRU) to receive and transmit data on multiple LTE component carriers simultaneously in both uplink and downlink. This is referred to as carrier aggregation.
Receiving and transmitting on multiple carriers significantly increases the power consumption of the WTRU. It is known that the power consumption of the analog front-end, (which counts as a significant fraction of total power consumption at the WTRU), is linearly proportional to the bandwidth or a plurality of basic frequency blocks (i.e., component carriers) that are aggregated. Activating and deactivating additional component carriers on demand and rapidly is critical to saving WTRU resources, (e.g., hybrid automatic repeat request (HARQ) processing (including channel quality indicator (CQI) and sounding reference signal (SRS) reporting), buffer occupancy and buffer management, (e.g., buffer status report (BSR) reporting) and scheduling processing), and providing savings of power consumption.